The present invention relates to polishing compositions, particularly compositions for polishing memory hard discs of computers, word processors or the like.
A memory hard disc is usually made in a process where a surface of a substrate of aluminium is polished, and a layer of magnetic storage medium is formed on the smoothed surface of the substrate. In recent years, a memory hard disc has been made by a process where a layer of non-electrolysis nickel plating, also called chemical nickel plating, or a layer of alumite is formed on a substrate of aluminium to form a pre-treated surface, the pre-treated surface is polished, and a layer of magnetic storage medium is formed on the smoothed pre-treated surface.
In any memory hard disc, a general-purpose polishing slurry formulated by suspending a polishing agent of aluminium oxide in water is used for the polishing.
However, the general-purpose polishing slurry is low in the polishing amount and low in the polishing efficiency for a memory hard disc. Moreover, surface defects such as orange peels, may be produced and the polishing quality is low, and therefore the general-purpose polishing slurry is not practicable. Consequently, a polishing composition for a memory hard disc has been desired.